/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#include <mapnik/plugin.hpp>
#include <stdexcept>

#ifdef _WIN32
#define NOMINMAX
#include <windows.h>
#define handle  HMODULE
#define dlsym   GetProcAddress
#define dlclose FreeLibrary
#define dlerror GetLastError
#define MAPNIK_SUPPORTS_DLOPEN
#else
#ifdef MAPNIK_HAS_DLCFN
#include <dlfcn.h>
#define MAPNIK_SUPPORTS_DLOPEN
#endif
#define handle void*
#endif

// TODO - handle/report dlerror

namespace mapnik {

struct _mapnik_lib_t
{
    handle dl;
};

PluginInfo::PluginInfo(std::string const& filename, std::string const& library_name)
    : filename_(filename)
    , name_()
    , module_(new mapnik_lib_t)
{
#ifdef _WIN32
    if (module_)
        module_->dl = LoadLibraryA(filename.c_str());
    if (module_ && module_->dl)
    {
        callable_returning_string name_call =
          reinterpret_cast<callable_returning_string>(dlsym(module_->dl, library_name.c_str()));
        if (name_call)
            name_ = name_call();
        callable_returning_void init_once =
          reinterpret_cast<callable_returning_void>(dlsym(module_->dl, "on_plugin_load"));
        if (init_once)
        {
            init_once();
        }
    }
#else
#ifdef MAPNIK_HAS_DLCFN
    if (module_)
        module_->dl = dlopen(filename.c_str(), RTLD_LAZY);
    if (module_ && module_->dl)
    {
        callable_returning_string name_call =
          reinterpret_cast<callable_returning_string>(dlsym(module_->dl, library_name.c_str()));
        if (name_call)
            name_ = name_call();
        callable_returning_void init_once =
          reinterpret_cast<callable_returning_void>(dlsym(module_->dl, "on_plugin_load"));
        if (init_once)
        {
            init_once();
        }
    }
#else
    throw std::runtime_error("no support for loading dynamic objects (Mapnik not compiled with -DMAPNIK_HAS_DLCFN)");
#endif
#endif
}

PluginInfo::~PluginInfo()
{
    if (module_)
    {
#ifdef MAPNIK_SUPPORTS_DLOPEN
        /*
          We do not call dlclose for plugins that link libgdal.
          This is a terrible hack, but necessary to prevent crashes
          at exit when gdal attempts to shutdown. The problem arises
          when Mapnik is used with another library that uses thread-local
          storage (like libuv). In this case GDAL also tries to cleanup thread
          local storage and leaves things in a state that causes libuv to crash.
          This is partially fixed by http://trac.osgeo.org/gdal/ticket/5509 but only
          in the case that gdal is linked as a shared library. This workaround therefore
          prevents crashes with gdal 1.11.x and gdal 2.x when using a static libgdal.
        */
        if (module_->dl && name_ != "gdal" && name_ != "ogr")
        {
#ifndef MAPNIK_NO_DLCLOSE
            dlclose(module_->dl), module_->dl = 0;
#endif
        }
#endif
        delete module_;
    }
}

void* PluginInfo::get_symbol(std::string const& sym_name) const
{
#ifdef MAPNIK_SUPPORTS_DLOPEN
    return static_cast<void*>(dlsym(module_->dl, sym_name.c_str()));
#else
    return nullptr;
#endif
}

std::string const& PluginInfo::name() const
{
    return name_;
}

bool PluginInfo::valid() const
{
#ifdef MAPNIK_SUPPORTS_DLOPEN
    if (module_ && module_->dl && !name_.empty())
        return true;
#endif
    return false;
}

std::string PluginInfo::get_error() const
{
    return std::string("could not open: '") + name_ + "'";
}

void PluginInfo::init()
{
    // do any initialization needed
}

void PluginInfo::exit()
{
    // do any shutdown needed
}

} // namespace mapnik
